Sounds like alternator and battery time. Your alternator isn't putting out enough to keep the battery charged which killed the battery since you were pretty much running off of it with a bad alternator.
I just changed the alternator on mine Friday. With a voltmeter hooked to the battery, the car was getting 12.3 volts at idle, and it would increase to 13.1 when you revved the engine. Now it's something like 14.2 at idle.
I would take the alternator and battery out and take them to like, an AutoZone to get checked out. The battery, depending on how old it is, might be able to be charged by them and you'll just need a replacement alt.
Oh, and when replacing it, BE CAREFUL to not cross-thread the two lower bolts that hold it in.